Class A/B switching?

[Shockfett]

Hello guys,

I'm trying to find a good article to understand how a A\B switches from each class. And I can't find anything the explains it completely. Does anyone know of a good article?

I have a X3 in the way. I read that it switches from A @15watts to B. I would like to know what that means. I'm not sure if it means if my speakers are 90db sensitive. At 8 watts I can get to 99db and still be at class A?


Thank you guys I really appreciate it a lot.

 

[Zen Mod]

Klunk! paper

 

[Vix]

Think of it like CVT, not Manual Transmission. You won't hear gears change 🙂

 

[Zen Mod]

Klunk!

 

[Shockfett]

So I can keep it in class A as long as I'm under 15watts correct? So at 90db sensitivity. I can reach 99db @8watts and stay in class A?

 

[Zen Mod]

you know , if Papa became deaf enough to not hear da Klunk! in amp properly made , I'm pretty sure that you and Mighty Moi are having at least 6 deaf ears , together

 

[Nelson Pass]

Big lesson is that the higher the bias, the less klunk when it does occur.

😎

 

[6L6]

I'm trying to find a good article to understand how a A\B switches from each class.

There is no switch. The circuit of a Class A amp and Class A/B amp can be identical except for the amount of bias. Lots of bias means that the amp must be physically big with a huge PSU, and large, very warm (read hot) heatsinks. This is expensive and inefficient, and is why most amps are not Class-A.

I'm not sure if it means if my speakers are 90db sensitive. At 8 watts I can get to 99db and still be at class A?

In theory, with your 90db speakers at 1M distance the SPL should be;
1W = 90db
2W = 93db
4W = 96db
8W = 99db
16W = 102db
32W = 105db
64W = 108db
128W = 111db
256W = 114db (yes, I know your amp doesn't have 250W)

So yes. There will be no klunk at 99db. 😀 😀 😀

But much, much, much more important than the mythical klunk (which doesn't exist🙂 ) is by this computation, you have 10db headroom above your 99db target before the amp clips.

 

[AndrewT]

..................... At 8 watts I can get to 99db and still be at class A?..............

8W into 8r0 requires an output current of 1.414Apk and an output voltage of 11.3Vpk.
To remain in ClassA @ 8W, the output stage must be able to output 1.414A of ClassA current.